The invention relates generally to high-pressure fluid jet nozzles and more particularly to an orifice jet nozzle assembly for waterjet cutting systems and the like that use high-pressure fluids to form a high-energy stream for solid material cutting and similar processes. The proper alignment of the orifice that forms the water stream is essential to proper function and accurate cutting. The orifice must also be replaced at frequent intervals. The process of orifice installation and alignment takes time and cannot be done by machine operators under field conditions. Furthermore, all current waterjet systems allow for only a single orifice per nozzle. The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide a means that allows for easy installation and alignment of orifices by operating waterjet system personnel, and allows for multiple orifices from a single nozzle that allow multiple waterjet streams. Accordingly, a suitable method is provided that allows easy replacement and alignment of orifices by field personnel, and allows multiple orifices in a single nozzle. The assembly can also be used to maintain consistent alignment with a down stream mixing tube, such as used in abrasive waterjet cutting.
The invention uses a spring disk to retain and align an orifice(s) on a smooth flat surface. The spring disk has a large outside diameter, one or more through-holes in area of center of its surface, and, concentric with the through-holes, shallow recesses (or counterbores). The wells are slightly larger in diameter than the particular orifice to be mounted and slightly shallower than the thickness of the orifice. The orifice(s) is (are) placed into the recesses (counterbores). When installing an orifice, a small amount of a viscous liquid, such as water with soap, will prevent the orifice(s) from falling out of the recess(es). The nozzle cap is made with a recess (counterbore) that has a diameter that is slightly larger than the spring disk and has through-holes that are concentric with the orifice hole. The recessed surface of the cap is lapped so that it is very flat and smooth. The diameter of the spring disk is larger than the inner diameter of the inlet tube. When the cap is mounted on the Inlet tube and tightened, the outer diameter of the spring disk is forced to flex to the cap surface while the center portion is restrained by the orifice that is resting on the same cap surface. This imposes a force (a preload) on the orifice(s) which acts on the lapped surface of the cap. The force on the orifice(s) is a function of the diameter, thickness and displacement of the outer portion of the spring disk. This force Is not sufficient to prevent fluid from leaking around the orifice. The principle that works to provide total sealing is a self-actuating concept that uses the difference in area between the top of the orifice and the bottom that is resting on the lapped surface. The hole through the cap is larger than the diameter of the bore through the orifice. The inlet area of the orifice (exposed to high pressure fluid) is larger than the area of the orifice resting on the lapped surface. The resulting effect is that the stress acting on the orifice at the lapped surface is much greater than the stress at the inlet area of the orifice. As a result, when the lapped area is smooth, fluid cannot leak past the orifice. In addition, the spring disk may be bored and counterbored to allow placement of several orifices at specified distances from each other to permit multiple waterjets for simultaneous cutting.